U.S. Pat. No. 4,758,541 relates to a zirconia sintered body comprising, in addition to ZrO2, Y2O3 and TiO2, 0.1 to 3 mol % of an oxide of a rare earth element of the lanthanum group having a fluorescence-radiating property as well as a high translucence.
U.S. Pat. No. 6,709,694 relates to the coloring of ceramics by means of ionic or complex-containing solutions. Solutions preferred for this contain defined concentrations of at least one of the salts or complexes of the rare earth elements or the elements of the subgroups.
U.S. Pat. No. 6,713,421 relates to blanks comprising zirconium oxide-based ceramic with an addition of 0.1 to 0.50 wt.-% of at least one of the oxides of the elements aluminium, gallium, germanium, indium and their use.
US 2007/0292597 relates to compositions based on ZrO2 and single- and multi-colored blanks made from oxide ceramics and a process for their preparation, in which oxide ceramic powder is coated with a colouring substance.
EP 1 818 318 A2 describes a production method of a dental ceramics material comprising the step of mixing a pink coloring agent and a yellow coloring agent at a certain mixing ratio with zirconium oxide. As the pink coloring agent manganese oxide is used and as the yellow coloring agent vanadium oxide is used. These additives absorb light.
US 2005/0060948 refers to a method of making glass-ceramics comprising Al2O3, rare earth oxides, at least one of ZrO2 or HfO2 and at least one of Nb2O5 or Ta2O5.
U.S. Pat. No. 5,263,858 is directed to an ivory-colored zirconia sintered body containing stabilizer-containing ZrO2 as a main component and also containing certain amounts of Er2O3, Pr6O11, Fe2O3 and ZnO.
There is still room for improvement especially with regard to the requirements to be fulfilled with respect to modern dental materials. Many of the commercially available dental restorations still do not show the appearance of natural dental teeth.
However, patients and dentists nowadays have an increasing demand for aesthetic dentures.
Thus, it is one object of the invention to provide a dental article which can be used for making aesthetic dental restorations.